Methylphenidate and amantadine to stimulate reawakening in comatose patients resuscitated from cardiac arrest

Exploration of resting-state brain functional connectivity as preclinical markers for arousal prediction in prolonged disorders of consciousness: A pilot study based on functional near-infrared spectroscopy

BACKGROUND

There is no diagnostic assessment procedure with moderate or strong evidence of use, and evidence for current means of treating prolonged disorders of consciousness (pDOC) is sparse. This may be related to the fact that the mechanisms of pDOC have not been studied deeply enough and are not clear enough. Therefore, the aim of this study was to explore the mechanism of pDOC using functional near-infrared spectroscopy (fNIRS) to provide a basis for the treatment of pDOC, as well as to explore preclinical markers for determining the arousal of pDOC patients.

METHODS

Five minutes resting-state data were collected from 10 pDOC patients and 13healthy adults using fNIRS. Based on the concentrations of oxyhemoglobin (HbO) and deoxyhemoglobin (HbR) in the time series, the resting-state cortical brain functional connectivity strengths of the two groups were calculated, and the functional connectivity strengths of homologous and heterologous brain networks were compared at the sensorimotor network (SEN), dorsal attention network (DAN), ventral attention network (VAN), default mode network (DMN), frontoparietal network (FPN), and visual network (VIS) levels. Univariate binary logistic regression analyses were performed on brain networks with statistically significant differences to identify brain networks associated with arousal in pDOC patients. The receiver operating characteristic (ROC) curves were further analyzed to determine the cut-off value of the relevant brain networks to provide clinical biomarkers for the prediction of arousal in pDOC patients.

RESULTS

The results showed that the functional connectivity strengths of oxyhemoglobin (HbO)-based SEN∼SEN, VIS∼VIS, DAN∼DAN, DMN∼DMN, SEN∼VIS, SEN∼FPN, SEN∼DAN, SEN∼DMN, VIS∼FPN, VIS∼DAN, VIS∼DMN, HbR-based SEN∼SEN, and SEN∼DAN were significantly reduced in the pDOC group and were factors that could reflect the participants' state of consciousness. The cut-off value of resting-state functional connectivity strength calculated by ROC curve analysis can be used as a potential preclinical marker for predicting the arousal state of subjects.

CONCLUSION

Resting-state functional connectivity strength of cortical networks is significantly reduced in pDOC patients. The cut-off values of resting-state functional connectivity strength are potential preclinical markers for predicting arousal in pDOC patients.

The effect of amantadine treatment on neurological outcome and mortality in mechanically ventilated severe head trauma patients in intensive care unit

This study aims to investigate the effect of amantadine use on neurological outcomes and mortality in patients with severe traumatic brain injury (TBI) (Glasgow coma score [GCS] between 3 and 8) who have been followed up on mechanical ventilators in the intensive care unit (ICU). Data from the hospital's electronic records were retrospectively searched. Patients over 18 years of age, with severe brain trauma (GCS between 3-8), who were treated with endotracheal intubation and invasive mechanical ventilation at admission to the ICU, and who were treated with Amantadine hydrochloride at least once in the first week of follow-up were included in the study. To evaluate the patients' neurological outcomes, the GCS and FOUR scores were used. GCS and FOUR scores were recorded on the 1st, 3rd, and 7th days of the first week. In addition, the score difference between the 1st and 7th day was calculated for both scores. The patients were divided into 2 groups: those receiving amantadine treatment (Group A, n = 44) and the control group (Group C, n = 47). The median age of all patients was 39 (18-81) (P = .425). When Group A and Group C were compared, no statistically significant results were found between the 1st, 3rd, and 7th day GCS values (P = .474, P = .483, and P = 329, respectively). However, the difference in GCS values between day 1 and day 7 (∆ GCS 7-1) was statistically significant (P = .012). Similarly, when Group A and Group C were compared, no statistically significant results were found between the 1st, 3rd, and 7th day FOUR score values (P = .948, P = .471, and P = .057, respectively). However, the FOUR score values between day 1 and day 7 (∆ FOUR score 7-1) were statistically significant (P = .004). There was no statistically significant difference among the groups in terms of ICU length of stay, duration of non-ICU hospital stay, and length of hospital stay (P = .222, P = .175, and P = .067, respectively). Amantadine hydrochloride may help improve neurological outcomes in patients with severe TBI. However, further research is needed to investigate this topic.

Does amantadine improve cognitive recovery in severe disorders of consciousness after aneurysmal subarachnoid hemorrhage? A double-blind placebo-controlled study

BACKGROUND

Severe disorders of consciousness (sDoC) are a common sequela of aneurysmal subarachnoid hemorrhages (aSAH), and amantadine has been used to improve cognitive recovery after traumatic brain injury.

OBJECTIVE

This study evaluated the effect of amantadine treatment on consciousness in patients with sDoC secondary to aSAH.

METHODS

This double-center, randomized, prospective, cohort study included patients ≥ 18 years old with sDoC after aSAH from February 2020 to September 2023. Individual patient data of patients were pooled to determine the effect of amantadine, in comparison to placebo. The primary outcomes at 3 and 6 months after the ictus were evaluated using the modified Rankin scale (mRS) and Glasgow outcome scale (GOS). In addition to all-cause mortality, secondary endpoints were assessed weekly during intervention by scores on Rappaport's Disability Rating Scale (RDRS) and Coma Recovery Scale-Revised (CRSR).

RESULTS

Overall, 37 patients with sDoC and initial Glasgow Coma Scale (GCS) varying between 3 and 11 were recruited and randomized to amantadine (test group, n = 20) or placebo (control group, n = 17). The average age was 59.5 years (28 to 81 year-old), 24 (65%) were women, and the mean GCS at the beginning of intervention was 7.1. Most patients evolved to vasospasm (81%), with ischemia in 73% of them. The intervention was started between 30 to 180 days after the ictus, and administered for 6 weeks, with progressively higher doses. Neither epidemiological characteristics nor considerations regarding the treatment of the aneurysm and its complications differed between both arms. Overall mortality was 10.8% (4 deaths). During the study, four patients had potential adverse drug effects: two presented seizures, one had paralytic ileus, and another evolved with tachycardia; the medication was not suspended, only the dose was not increased. At data opening, 2 were taking amantadine and 2 placebo.

CONCLUSION

Despite some good results associated with amantadine in the literature, this study did not find statistically significant positive effects in cognitive recovery in patients with delayed post-aSAH sDoC. Further large randomized clinical trials in patients' subgroups are needed to better define its effectiveness and clarify any therapeutic window where it can be advantageous.

Detecting signatures of consciousness in acute brain injury after stimulation with apomorphine and methylphenidate: protocol for a placebo-controlled, randomized, cross-over study

Introduction

Acute brain injury can lead to states of decreased consciousness, that is, disorder of consciousness (DoC). Detecting signs of consciousness early is vital for DoC management in the intensive care unit (ICU), neurorehabilitation and long-term prognosis. Our primary objective is to investigate the potential of pharmacological stimulant therapies in eliciting signs of consciousness among unresponsive or low-responsive acute DoC patients.

Methods

In a placebo-controlled, randomised, cross-over setting, we evaluate the effect of methylphenidate and apomorphine in 50 DoC patients with acute traumatic or non-traumatic brain injury admitted to the ICU. Patients are examined before and after administration of the trial drugs using (1) neurobehavioural scales to determine the clinical level of consciousness, (2) automated pupillometry to record pupillary responses as a signature for awareness and (3) near-infrared spectroscopy combined with electroencephalography to record neurovascular coupling as a measure for cortical activity. Primary outcomes include pupillary dilations and increase in cortical activity during passive and active paradigms.

Ethics

The study has been approved by the ethics committee (Journal-nr: H-21022096) and follows the principles of the Declaration of Helsinki. It is deemed to pose minimal risks and to hold a significant potential to improve treatment options for DoC patients. If the stimulants are shown to enhance cortical modulation of pupillary function and neurovascular coupling, this would warrant a large multicentre trial to evaluate their clinical impact.

Dissemination

Results will be available on EudraCT, clinicaltrialsregister.eu and published in an international peer-reviewed journal.

Trial registration number

EudraCT Number: 2021-001453-31.

Aminoadamantanes: from treatment of Parkinson's and Alzheimer's disease to symptom amelioration of long COVID-19 syndrome?

INTRODUCTION

The aminoadamantanes amantadine and memantine are well known. They mainly act as N-methyl-D-aspartate antagonists.

AREAS COVERED

The antiviral drug amantadine moderately ameliorates impaired motor behavior in patients with Parkinson's disease. Memantine provides beneficial effects on memory function in patients with advanced Alzheimer's disease already treated with acetylcholine esterase inhibitors. Both compounds counteract impaired monoamine neurotransmission with associated symptoms, such as depression. They improve vigilance, lack of attention and concentration, fatigue syndromes according to clinical findings in patients with chronic neurodegenerative processes. Their extrasynaptic N-methyl-D-Aspartate receptor blockade weakens a prolonged influx of Ca²⁺ ions as the main responsible components of neuronal excitotoxicity. This causes neuronal dying and associated functional deficits.

EXPERT OPINION

We suggest aminoadamantanes as future therapies for amelioration of short- and long-term consequences of a COVID 19 infection. Particularly the extended-release amantadine formulations will be suitable. They showed better clinical efficacy compared with the conventional available compounds. Amantadine may particularly be suitable for amelioration of fatigue or chronic exhaustion, memantine for improvement of cognitive deficits. Clinical research in patients, who are affected by the short- and long-term consequences of a COVID 19 infection, is warranted to confirm these still hypothetical putative beneficial effects of aminoadamantanes.

Pharmacologic Therapies to Promote Recovery of Consciousness

Pharmacologic interventions are commonly used to support rehabilitation efforts of patients with disorders of consciousness (DoC). The 2018 practice guidelines recommend amantadine in adults with traumatic DoC to promote functional recovery, though several other stimulants are used off-label in clinical practice and trials, such as methylphenidate, bromocriptine, levodopa, and zolpidem. Differences in the mechanisms of action, adverse effects, pharmacokinetics, and drug-drug interactions should be considered when selecting the best agent for each individual patient. Overall, pharmacologic stimulants may provide a safe and inexpensive pathway to increased functionality and participation in rehabilitation. This article provides a concise summary of scientific evidence supporting the use of pharmacologic therapies to stimulate recovery of consciousness in patients with DoC.

Stability of extemporaneously prepared preservative-free methylphenidate 5 mg/mL intravenous solution

DISCLAIMER

In an effort to expedite the publication of articles , AJHP is posting manuscripts online as soon as possible after acceptance. Accepted manuscripts have been peer-reviewed and copyedited, but are posted online before technical formatting and author proofing. These manuscripts are not the final version of record and will be replaced with the final article (formatted per AJHP style and proofed by the authors) at a later time.

PURPOSE

To advance the implementation of consciousness-promoting therapies in patients with acute disorders of consciousness, the availability of potential therapeutic agents in formulations suitable for administration in hospitalized patients in the presence of complex comorbid conditions is paramount. The purpose of this study is to evaluate the long-term stability of extemporaneously prepared preservative-free methylphenidate hydrochloride (HCl) 5 mg/mL intravenous solution for experimental use.

METHODS

A methylphenidate 5 mg/mL solution was prepared under proper aseptic techniques with Methylphenidate Hydrochloride, USP, powder mixed in sterile water for solution. Methylphenidate HCl 5 mg/mL solution was sterilized by filtration technique under USP <797>-compliant conditions. Samples were stored refrigerated (2-8°C) and analyzed at approximately days 1, 30, 60, 90, 180, and 365. At each time point, chemical and physical stability were evaluated by visual inspection, pH measurement, membrane filtration procedure, turbidometric or photometric technique, and high-performance liquid chromatography analysis.

RESULTS

Over the 1-year study period, the samples retained 96.76% to 102.04% of the initial methylphenidate concentration. There was no significant change in the visual appearance, pH level, or particulate matter during the study period. The sterility of samples was maintained and endotoxin levels were undetectable throughout the 1-year stability period.

CONCLUSION

Extemporaneously prepared preservative-free methylphenidate 5 mg/mL intravenous solution was physically and chemically stable at 32, 61, 95, 186, and 365 days when stored in amber glass vials at refrigerated temperatures (2-8°C).

Does amantadine maintain function in long-established brain injury? A single case experimental design

OBJECTIVE

The role of dopamine agonist (DA) in restoring consciousness and cognition in recovery phase following acquired brain injury (ABI) is established ^(1-5). The role in later recovery is less well defined. We report a single case experimental design (SCED) trial of amantadine demonstrating improvement in function, six years following ABI.

METHOD

A scoring system based on established abilities in personal care and interaction was used to identify tasks with component actions, 34 actions in total, each ranked in terms of quality of response to a request or prompt. Actions were scored on maintenance dose amantadine; on withdrawal; and after reintroduction. Daytime sleep duration was also recorded.

RESULTS

At 3^rd and 5^th weeks post withdrawal, deterioration was noted in 27 of 34 graded activities. At 3^rd and 5^th weeks following reintroduction, all but 3 grades returned to baseline or better. Afternoon sleep duration increased from 35 to 80 minutes during withdrawal period returning towards baseline on amantadine resumption.

CONCLUSION

We believe this provides evidence for benefit of amantadine in sustaining function following ABI. The SCED model used provides a template for others to use to identify comparable change in similar trials.

Dual Neurostimulant Therapy May Optimize Acute Neurorecovery for Severe Traumatic Brain Injuries

BACKGROUND

Neurostimulants (NS) can be used to treat patients with a traumatic brain injury (TBI) with altered levels of consciousness. We sought to determine if amantadine alone (monotherapy) versus amantadine + methylphenidate (dual therapy) would correlate with better neurorecovery (NR) among acutely hospitalized patients with a severe TBI.

METHODS

We performed a retrospective review of adult patients admitted to our level I trauma center from 2016-2019 with a severe TBI. NR was calculated by dividing the difference between admission and discharge Glasgow Coma Scale (GCS) scores by 12. Resulting ratios were used to divide the cohort into two groups: excellent NR (1) and non-excellent NR (<1).

RESULTS

A total of 76 patients comprised the cohort; 19.7% (n = 15) had excellent NR. The excellent NR group had a larger proportion of patients receiving dual therapy compared to the non-excellent group (86.7% versus 59%, P = 0.04). In monotherapy (n = 27), amantadine was initiated 13 (8-20) d following injury and treatment lasted 7 (2-16) d. In dual therapy (n = 49), amantadine was initiated 12 (6-19) d following injury and continued for 9 (4-25.5) d. Methylphenidate was initiated 15 (7-20.5) d following injury and continued for 5 (2-13.5) d. After adjusting for confounders, dual versus monotherapy predicted excellent NR (OR 5.4, 95% CI 1.2 - 38.9, P = 0.03).

CONCLUSIONS

During the acute hospitalization for a severe TBI, dual NS therapy compared to monotherapy is associated with an increased likelihood of excellent NR. Larger prospective trials are warranted to validate these findings.

[Results of treatment with intravenous amantadine sulfate (PK-Merz) patients with chronic disorders of consciousness]

The article presents literature review of the recent publications devoted to the drugs with dopaminergic, antiglutamatergic and GABA-ergic effects in the treatment of patients with vegetative state/areactive wakefulness syndrome (VS/AWS). The authors analyzed their own results of the effects of intravenous form of amantadine sulfate (PK Merz) in 142 VS/AWS patients caused by different etiological factors. Depending on the dominant neurological symptoms, patients were divided into three main groups: areactive type of course (group 1 - 61 patients), predominance of primitive limbic reactions (group 2 - 35 patients) and predominance of extrapyramidal symptoms (group 3 - 46 patients). Therapy results were evaluated one month later by CRS-R scale, which showed that the most distinct positive dynamics was observed in group 3.

Associations Between Amantadine Usage, Gait, and Cognition in PSP: A post-hoc Analysis of the Davunetide Trial

Introduction: Amantadine anecdotally improves gait in progressive supranuclear palsy (PSP) but definitive data is lacking. We investigated associations between amantadine usage, gait, cognition, and activities of daily living in 310 subjects with PSP using data from the davunetide trial.

Method: We compared baseline demographics, PSP Rating Scale (PSPRS), Repeat Battery for the Assessment of Neuropsychological Status (RBANS), and Schwab and England Activities of Daily Living (SEADL) scores between subjects taking vs. not taking amantadine using chi-square tests for categorical variables and independent sample t-tests for continuous variables. Using the general linear model (GLM), we tested whether group status predicted total PSPRS, PSPRS-gait and midline, total RBANS, RBANS-attention, and SEADL before and after the 52-weeks follow-up.

Results: Subjects taking vs. not taking amantadine were similar at baseline, except subjects taking amantadine had a higher Clinical Global Impression (CGI) Score (p = 0.01). However, the CGI change score did not differ between groups at week 52 (p = 0.10). Using GLM models (controlling for covariates), we found that subjects taking vs. not taking amantadine did not significantly predict total PSPRS, PSPRS-gait and midline, total RBANS, RBANS-attention, or SEADL at baseline, week 52, or the change score between baseline and week 52.

Discussion: This post-hoc analysis of the davunetide trial did not find an association between amantadine and gait or cognitive measures in PSP, but was not powered to find such a difference. Future studies should still examine amantadine for symptomatic benefit in multiple PSP subtypes.

Sudden Cardiac Arrest Survivorship: A Scientific Statement From the American Heart Association

Cardiac arrest systems of care are successfully coordinating community, emergency medical services, and hospital efforts to improve the process of care for patients who have had a cardiac arrest. As a result, the number of people surviving sudden cardiac arrest is increasing. However, physical, cognitive, and emotional effects of surviving cardiac arrest may linger for months or years. Systematic recommendations stop short of addressing partnerships needed to care for patients and caregivers after medical stabilization. This document expands the cardiac arrest resuscitation system of care to include patients, caregivers, and rehabilitative healthcare partnerships, which are central to cardiac arrest survivorship.

Amantadine and memantine: a comprehensive review for acquired brain injury

This comprehensive review discusses clinical studies of patients following brain injuries (traumatic, acquired, or stroke), who have been treated with amantadine or memantine. Both amantadine and memantine are commonly used in the acute rehabilitation setting following brain injuries, despite their lack of FDA-approval for neuro-recovery. Given the broad utilization of such agents, there is a need to review the evidence supporting this common off-label prescribing. The purpose of this review is to describe the mechanisms of action for memantine and amantadine, as well as to complete a comprehensive review of the clinical uses of these agents. We included 119 original, clinical research articles from NCBI Medline, published before 2019. We focused on the domains of neuroplasticity, functional recovery, motor recovery, arousal, fatigue, insomnia, behavior, agitation, and cognition. Most of the existing research supporting the use of amantadine and memantine in recovery from brain injuries was done in very small populations, limiting the significance of conclusions. While most studies are positive; small effect sizes are usually reported, or populations are subject to bias. Furthermore, evidence is so limited that this review includes research regarding both acute and chronic acquired brain injury populations. Fortunately, reported short-term side effects generally are modest, and stop soon after amantadine/memantine is discontinued. However, responses are inconsistent, and the phenotype of responders remains elusive.

Effect of Rehabilitation Treatments on Disability in Persons With Disorders of Consciousness: A Propensity Score Study

OBJECTIVE

To evaluate the effects of rehabilitation (physical and cognitive) treatments on the diagnosis severity and Disability Rating Scale (DRS) scores, adjusted for a number of potential confounders measured at baseline, in a large cohort of patients with disorders of consciousness across time.

DESIGN AND SETTING

An observational, longitudinal (2 evaluations), multicenter project was made in 90 Italian centers.

PARTICIPANTS

Patients (N=364) with a diagnosis of disorders of consciousness.

MAIN OUTCOME MEASURES

Primary outcome was the severity of diagnosis, expressed on an ordinal scale (Other<MCS<VS<death). In the Other group were included patients who emerged from an MCS and recovered consciousness. The secondary outcome was the DRS score (range of 0-30 with 30 being the worst value). The DRS is a tool used to define the level of residual disability, commonly used to classify the level of functional impairment in patients with acquired brain injury. Both outcomes were measured for each wave.

RESULTS

A total of 364 subjects having a complete set of demographic, clinical, and pharmacologic data were included in the propensity score (PS) analysis. Results showed that the rehabilitation treatments (physical and cognitive) reduced the clinical worsening over time in both severity diagnosis and DRS (around 6.5 points) in patients with disorders of consciousness across different propensity score strategies (ie, PS matching, PS adjustment, and PS-weighted procedures). In addition, cognitive protocols seem to be limited to patients with a median value of DRS=23.

CONCLUSIONS

Our propensity score analysis suggests that rehabilitation treatment protocols seem effective and should be applied to a broader spectrum of patients with disorders of consciousness.

Neurostimulant use is associated with improved survival in comatose patients after cardiac arrest regardless of electroencephalographic substrate

AIM

Identify EEG patterns that predict or preclude favorable response in comatose post-arrest patients receiving neurostimulants.

METHODS

We examined a retrospective cohort of consecutive electroencephalography (EEG)-monitored comatose post-arrest patients. We classified the last day of EEG recording before neurostimulant administration based on continuity (continuous/discontinuous), reactivity (yes/no) and malignant patterns (periodic discharges, suppression burst, myoclonic status epilepticus or seizures; yes/no). In subjects who did not receive neurostimulants, we examined the last 24h of available recording. For our primary analysis, we used logistic regression to identify EEG predictors of favorable response to treatment (awakening).

RESULTS

In 585 subjects, mean (SD) age was 57 (17) years and 227 (39%) were female. Forty-seven patients (8%) received a neurostimulant. Neurostimulant administration independently predicted improved survival to hospital discharge in the overall cohort (adjusted odds ratio (aOR) 4.00, 95% CI 1.68-9.52) although functionally favorable survival did not differ. No EEG characteristic predicted favorable response to neurostimulants. In each subgroup of unfavorable EEG characteristics, neurostimulants were associated with increased survival to hospital discharge (discontinuous background: 44% vs 7%, P=0.004; non-reactive background: 56% vs 6%, P<0.001; malignant patterns: 63% vs 5%, P<0.001).

CONCLUSION

EEG patterns described as ominous after cardiac arrest did not preclude survival or awakening after neurostimulant administration. These data are limited by their observational nature and potential for selection bias, but suggest that EEG patterns alone should not affect consideration of neurostimulant use.

Disorders of Consciousness

Disorder of consciousness (DOC) is a state of prolonged altered consciousness, which can be categorized into coma, vegetative state, or minimally conscious state based on neurobehavioral function. The pathophysiology of DOC is poorly understood but recent advances in neuroimaging and advanced electrophysiological techniques may provide an improved understanding for the neural network involved with consciousness. The primary aim of DOC rehabilitation programs is to promote arousal while preventing secondary medical complications while providing education and training to families. Treatment interventions include both pharmacologic and nonpharmacologic programs, but there are currently no consensus treatment guidelines for individuals with DOC.

Postcardiac Arrest Management

Cardiac arrest afflicts more than 300,000 persons annually in North America alone. Advances in systematic, regimented postresuscitation care have lowered mortality and improved neurologic outcomes in select cohorts of patients over the last decade. Postcardiac arrest care now comprises its own link in the chain of survival. For most patients, high-quality postcardiac arrest care begins in the Emergency Department. This article reviews the evidence and offers treatment strategies for the key components of postcardiac arrest care.

Awakening and withdrawal of life-sustaining treatment in cardiac arrest survivors treated with therapeutic hypothermia*

OBJECTIVES

To characterize the prevalence of withdrawal of life-sustaining treatment, as well as the time to awakening, short-term neurologic outcomes, and cause of death in comatose survivors of out-of-hospital resuscitated cardiopulmonary arrests treated with therapeutic hypothermia.

DESIGN

Single center, prospective observational cohort study of consecutive patients with out-of-hospital cardiopulmonary arrests.

SETTING

Academic tertiary care hospital and level one trauma center in Minneapolis, MN.

PATIENTS

Adults with witnessed, nontraumatic, out-of-hospital cardiopulmonary arrests regardless of initial electrocardiographic rhythm with return of spontaneous circulation who were admitted to an ICU.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The study cohort included 154 comatose survivors of witnessed out-of-hospital cardiopulmonary arrests who were admitted to an ICU during the 54-month study period. One hundred eighteen patients (77%) were treated with therapeutic hypothermia. The mean age was 59 years, 104 (68%) were men, and 83 (54%) had an initial rhythm of ventricular tachycardia or fibrillation. Only eight of all 78 patients (10%) who died qualified as brain dead; and 81% of all patients (63 of 78) who died did so after withdrawal of life-sustaining treatment. Twenty of 56 comatose survivors (32%) treated with hypothermia who awoke (as defined by Glasgow Motor Score of 6) and had good neurologic outcomes (defined as Cerebral Performance Category 1-2) did so after 72 hours.

CONCLUSIONS

Our study supports delaying prognostication and withdrawal of life-sustaining treatment to beyond 72 hours in cases treated with therapeutic hypothermia. Larger multicenter prospective studies are needed to better define the most appropriate time frame for prognostication in comatose cardiac arrest survivors treated with therapeutic hypothermia. These data are also consistent with the notion that a majority of out-of-hospital cardiopulmonary arrest survivors die after a decision to withdrawal of life-sustaining treatment and that very few of these survivors progress to brain death.

Pharmacotherapy for disorders of consciousness: are 'awakening' drugs really a possibility?

Disorders of consciousness, including the coma state, vegetative state and minimally conscious state, are among the least understood and least curable conditions in modern neurology. Structural or functional injuries may produce impairments in the neuronal circuits (the ascending reticular activating system and thalamocortical loops) responsible for maintaining the wakefulness state and awareness, associated with a change in neurotransmitter concentrations. Pharmacological agents that are able to restore the levels of neurotransmitters and, consequently, neural synaptic plasticity and functional connectivity of consciousness networks, may play an important role as drugs useful in improving the consciousness state. Currently, there is growing interest in the scientific community with regard to pharmacological agents that act on the gamma amino-butyric acid (GABA) system, such as zolpidem and baclofen, and monoamine systems, such as dopaminergic agents and some antidepressants. The purpose of this article is to provide a comprehensive overview of these potential 'awakening' drugs in patients with disorders of consciousness. The possible mechanisms by which these drugs may exert their effects in promoting recovery of consciousness are discussed, highlighting how many findings are often the result of sporadic events rather than prospective controlled trials or implementation of standard treatment guidelines.